1. Field of the Invention
The present invention relates to a gas circuit breaker and a circuit breaker for a gas insulated switching device.
2. Description of the Related Art
A gas insulated switching device including a bus container is a device that is disposed between a three-phase high-voltage power supply and an air power transmission line in a substation or the like and detects an abnormal current such as a lightening surge and shuts off an electric current. The gas insulated switching device is configured by a bushing that receives electric power from the three-phase high-voltage power supply, a gas circuit breaker, a bus container that houses a three-phase collective bus conductor gas-insulated to distribute electric power from the bushing to the gas circuit breaker, a disconnecting switch, an earthing device, and the like.
In recent years, a spring operation device, a driving source of which is a metal spring, is extensively applied to a gas circuit breaker used in a high-voltage power system. This is because oil is likely to leak from an accumulator, a hydraulic pump, and the like in a hydraulic operation device applied in the past.
As background art in this technical field applied with the spring operation device, there are JP-A-2015-097140 (Patent Literature 1), JP-A-2013-065480 (Patent Literature 2), JP-A-2010-080412 (Patent Literature 3), JP-A-2005-228713 (Patent Literature 4), and JP-T-2002-536796 (Patent Literature 5). Patent Literature 1 mentions that “a cylindrical breaking spring case 34 and a closing spring case 35 connected to a side of a mechanism unit 15 are fixed to a common pedestal 1 by legs 10d”. 
Patent Literature 2 mentions that “a breaking spring 12 and a closing spring 13 are provided in an upper part of a housing 14 as a breaking driving source of an operation mechanism 10”.
Patent Literature 3 mentions that “a breaking operation unit 403 including a breaking spring 26 and a closing control mechanism 402 that holds and opens a closing spring 28 are housed in a spring operation mechanism 400 in an operation box 104, and the breaking spring 26 and the closing spring 28 are attached in lower parts”.
Patent Literature 4 mentions that “respective one ends of a breaking spring 44 and a closing spring 42 are fixed to a frame lower part of a circuit breaker and respective other ends of the breaking spring 44 and the closing spring 42 are supported by a spring seat plate 70 and a spring seat plate 71”.
Patent Literature 5 mentions that “a driving case 25 is provided under a circuit breaker case 11, a spring driving device 26 including closing and breaking springs is housed in the driving case 25, and the respective springs are configured to extend in the vertical direction”.
A gas circuit breaker is configured from a breaking unit tank, a spring operation device, a mechanism unit, and the like. For example, Patent Literature 5 describes a structure in which a part of the spring operation device is fixed to a flange of the mechanism unit. However, the techniques described in Patent Literatures 1 to 5 do not take into account a deficiency in which the entire spring operation device vibrates according to an extending motion of a spring functioning as a driving source and efficiency of transmission of a driving force to a movable electrode of the breaking unit tank via the mechanism unit is deteriorated.